Electrophotographic copying machine

ABSTRACT

An electrophotographic copying machine which makes a plurality of copies from one original in one operation, that is one reciprocation of an original holder. During one going stroke of the original holder, the original is scanned many times through a plurality of slits arrayed in spaced-apart relation with each other by a suitable distance along the path of the original holder and projected upon a photosensitive member which is displaced in synchronism with the original holder, so that a plurality of electrostatic latent images of the same original may be formed upon the sensitive member.

D United States Patent 1151 3,661,455 Namiki et al. 1 51 May 9, 1972 541 ELECTROPHOTOGRAPHIC COPYING 3,419,327 12/1968 Oikawa et al. ..355/8 MACHINE 3,528,738 9 1970 Hodges .355/8 x R26,771 1/1970 Schwardt et al. ..355/54 [72] Inventors: Ryoichi Namiki, Tokyo; Masao Anga,

Kawasakl both of Japan Primary E.\'aminerSamuel S. Matthews [7 3] Assignee: Canon Kabushiki Kaisha, Tokyo, Japan Assistant Bummer-Fred L. Braun Filed: Feb. 26 1971 Attorneyward, McElhannon, Brooks & Fitzpatnck [21] Appl. No.: 119,192 [57] ABSTRACT An electrophotographic copying machine which makes a plu- [30] Foreign Application Priority Data rality of copies from one original in one operation, that is one I u 4 reciprocation of an original holder. During one going stroke of Mar Japan /195 8 the original holder, the original is scanned many times through 52 us. 01 355/14 355/8 355/46 a Plurality slits arrayed in Spaied'aian with each I I l 3 355/54 other by a suitable distance along the path of the original 51 im. (:1. ..G03g 15/04 holder and Projected p a photosensitive member which is [58] Field of Search ..355/3, 8, 11, 14, 46, 49,51, displaced in Symhronism with the Original holder, that 355/54, 66, 86, plurality of electrostatic latent images of the same original may be formed upon the sensitive member.

R f C'ted [56] e 4 Claims, 5 Drawing Figures UNITED STATES PATENTS 3,181,418 5/1965 Durlofsky ..355/l4 X PATENTEDMAY 91922 SHEET 1 [IF 3 PATENTEDMM 9 m2 SHEU 2 OF 3 PATENTEDMAY 9l972 SHEEI30F3 BACKGROUND OF THE INVENTION The present invention relates to generally an electrophotographic copying machine and more particularly to a slit-exposure type electrophotographic copying machine capable of producing more than two copies from a single original in one cyclic copying operation. 7

In the conventional electrophotographic copying machine of the type in which an original is exposed through a slit, an optical projection system is generally displaced in synchronism with the displacement of a photosensitive member between the latter and an original which is held in stationary position. The light or radiationimage of the original which is illuminated by a suitable light source is projected upon the photosensitive member by the scanning of the original through the slit of the moving optical projection system. In the conventional electrophotographic copying machine of the type described, in order to reproduce more than two copies from the same original, the reciprocation of the optical projection or scanning system must be cycled for each copy. Since no copying operation is carried out during the return stroke of the optical projection or scanning system to its original or initial position, the time interval required for the return stroke is wasted and the high speed copying operation is impossible. This defect is especially pronounced when a large number of copies is required from a single original at high speed.

To overcome this problem, there has been proposed a slitexposure type electrophotographic copying machine of the type in which both of an original and a photosensitive member are displaced in synchronism with each other on both sides of a stationary optical projection or scanning system. To attain .the high copying speed, the original is carried by a fast-moving endless belt. However this electrophotographic copying machine has a distinct defect that the thickness of an original to be copied is limited so that only an original in sheet form may be used.

One of the objects of the present invention is therefore to provide an electrophotographic copying machine capable of continuously making more than two copies in one cyclic operation at high speed.

Another object of the. present invention is to provide an electrophotographic copying machine in which a plurality of optical projection systems for exposure are held stationary so as to prevent the damages.

Another object of the present invention is to provide an electrophotographic copying machine in which any type of original in sheet or book may be placed upon an original holder whose upper surface is completely opened for this purose. P Another object of the present invention is to provide an electrophotographic copying machine especially adapted for use in the banks or the like where usually the predetermined number ofcopies ofa bill or the like must be made.

SUMMARY or THE. INVENTION In brief the present invention provides an electrophotographic copying machine in which a plurality of slits through which an original is scanned for exposure are disposed in spaced-apart relation with each other by a suitable distance along the path of an original holding and transport means which reciprocates and a plurality of optical projection systems are provided for projecting the light image of the original successively through the slits upon a photosensitive member which is displaced in synchronism with the original holding and transport means, whereby a plurality of copies may be made in one cyclic operation at a high speed.

The above and other objects, features and advantages of the present invention will become more apparent from the description of the preferred embodiment thereof taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THEPREFERREDEMBODIMENT Referring to FIG. 1, an original 1 is displaced in the direction indicated by XX with respect to a photoelectrically sensitive drum 4 rotating in the opposite direction sov that the original 1 may be projected upon the drum 4 at 0 point through slits 2, and 2, by-optical projection systems comprising illumination light sources 5 and projection lenses 3, and 3,. The original 1 is first projected through the slit 2 and then through the slit 2, while the original 1 is displaced in the direction indicated by the arrow in the conventional manner. In the instant embodiment, only two slits 2 and 2, are shown, but it should be noted that a number of copies to be reproduced by one stroke or displacement of the original 1 may be increased when the number of the slits 2 and the optical projection systems 3 and 5 is increased accordingly. As a consequence, the photocopying operation is carried out at high speed.

Referring to FIG. 2, the original OR in sheet is inserted through an original inlet 7 of a casing 6 of the photocopying machine and a reproduced copy 9 is discharged into a receiving tray 10. A photosensitive layer 12 consisting of a surface insulating layer, a photoconductive layer and a conducting or insulating layer in the order named is applied around the illustrating'the principle of periphery of a rotary drum '11 in the casing 6 and around the periphery of the rotary drum 11 are disposed a first charger 13, a simultaneous exposure-charging device 14,;a whole-surface illuminating device 15, a developing device 16, a third charger 1.7, an image transfer device 18 and a cleaning device 19 in the order named in the direction of rotation of the rotary drum 1].

The uniform positive or negative D.C. corona discharge is applied by the first charger 13 to the peripheral surface of the rotary drum 11. By the simultaneous exposure-charging means 14, the rotary drum 11 is applied with the AC. corona discharge or the DC. corona discharge with the polarity opposite to that given by the first charger l3 simultaneously when the light or radiation image of the original is projected upon the rotary drum 1], whereby the electrostatic latent image is formed.

Next by the whole-surface illumination'device 15 such as a fluorescent lamp the electrostatic latent image is uniformly illuminated so as to increase the action of the electrostatic latent image as the external field, thereby increasing the contrast of the latent image. By the developing device 16, the electrostatic latent image is developed into a positive image with the toner which is charged with the polarity opposite to that of the latent image. Alternatively, the electrostatic latent image may be developed into a negative image with the toner which is electrostatically charged with the same polarity with that of the latent image. It is preferable to employ a fur-brush or magnet brush developing method.

The third charger 17, which is not necessarily required, serves to applythe electrostatic charge with a suitable polarity to the toner image upon the rotary drum 11 so that the transfer of the toner image to a copying paper may be facilitated. The toner image is electrostatically transferred to the copying paper by the image transfer device 18 and the toner remained on the rotary drum 11 is cleaned by a cleaning roller 20 in the cleaning device 19.

So far the general construction and mode of operation of the instant embodiment have been described in brief, but it is noted that the novel features of the present invention are found especially in the device for transporting the original and the optical projection system for projecting the light or radiation image of the original upon the rotary drum as will be described in more detail hereinafter.

Device for Transporting Original in Sheet Form Referring to FIGS. 3 and 4 in general the original transport device comprises an original holder 25 which rides on rails 21, a pair of conveyors which are disposed on both sides of and below the original holder 25 and each of which consists a conveyor belt 22 and drive rollers 23 and 24 for transporting the original OR inserted through the inlet 7, a wire 26 for transporting the original holder 25, a pulley '27, a capstan 28, photoelectric effect elements 29, 30 and 31 and light sources 32, 33 and 34. As viewed from FIG. 4, the original holder 25 has two types of guides so that two different size originals may be selectively placed upon the original holder 25.

The original OR (for example a bill or the like) is inserted throughthe inlet 7 with the image faced up, onto the original holder 25 so that the light from the light source 32 to the photoconductive element 29 is interrupted. Therefore a switching circuit S1 in a control circuit shown in FIG. is actuated to energize an output relay K3 to close its contact K3, thereby energizing relays A and B. As a consequence a motor M6 is energized for driving the conveyor belt 22 to thereby automatically transport the original OR on the original holder 25 to a position 25,. As a consequence the light from the light sources 33 and 34 to the photoconductive elements 30 and 31 are interrupted so that both of switching circuits S3 and S2 are actuated to energize the output relays K4 and K5 to close their contacts K4 and K5. Therefore the relays A, B and C are energized to actuate a drum clutch thereby reciprocating the original holder 25 in the direction indicated by the arrow through the capstan 28, pulley 27 and wire 26. When the light is again intercepted by the photoconductive elements 29, 30 and 31 as the original holder 26 is moved away from the light sources 32, 33 and 34, the switching circuits S1, S2 and S3 are deactivated so that the output relays K3, K4 and K5 are deenergized to open their contacts K3, K4 and K5. As a consequence the relays A, B and C are deenergized to thereby stop the motor M6.

When theoriginal OR is fed slantly so that either of the light from the light sources 33 or 34 is intercepted by the photoconductive element 30 or 31, the motor M6 rotates in the direction for transporting the original so that the leading edge of the original OR may be positioned at a right angle relative to the direction of feed of the original. However, the drum clutch for transporting the original holder 25 is not actuated so that it remains in the initial position. When the original OR is correctly placed in position that is, when the light from the light sources 33 and 34 is interrupted from the photoconductive elements 30 and 31, the drum clutch is actuated so as to drive the original holder 25.

Upon completion of the going stroke of the original holder, a microswitch (fixed to the rotary drum and not shown) is actuated to thereby reverse the capstan 28 to return the original holder 25 to its original or initial position. Upon return of the original holder to its original or initial position, the light from the light sources 33 and 34 to the photoconductive elements 30 and 31 is interrupted so that the output relays K3 and K4 are energized to thereby energize the relays A and C. As the relay B is not energized, the auxiliary coil L of the motor M6 is energized in the reversed direction relative to the main coil L, so that the motor M6 is reversed in direction. As a consequence the conveyor belt 22 is also reversed in direction so that the original OR is discharged through the inlet 7. When the operator pulls out the original, the relay A is deenergized to thereby stop the motor M6. The position of the photoconductive element 29 relative to the conveyor belt 22 is so determined that unless the operator pulls out the original OR the relay A will not be deenergized. As a consequence, even when the operator inserts the next original into the photocopying machine, the motor M6 will not drive so as to place the next original onto the original holder 25.

A copy-number-setting dial (not shown) may be set to the desired number of copies to be reproduced from the same original. In this case when the original holder 25 returns to its original or initial position, the light from the light sources 33 and 34 to the photoconductive elements 30 and 31 is interrupted so that the original OR is slightly moved toward the left in FIG. 3 by the conveyor belt 22 to permit the light to enter again the photoconductive elements 30 and 31. Then the conveyor belt 22 is reversed in direction to move or place back the original onto the original holder 25, so that the interception of the light by the elements 30 and 31 is again interrupted and the original holder 25 is transported for exposure in the manner described above. This original transporting or reciprocating operation is cycled until the desired number of copies is reproduced. 1

One of the novel features of the present invention resides in the fact that two different originals may be reproduced on a single copying paper at the same time. For example when it is desired to reproduce the copies of a number of bills for one customer or the like, a card or the like hearing the customers name, address, deposit number, and the like may be placed in a position indicated by 25, upon the original holder 25 while the bills or the like placed in position at 25 may be successively reproduced in the manner described above so that the copies each bearing the same card and the different bill or the like may be obtained.

It is understood that instead of the conveyor belt 22, a plurality of feed rollers or the like may be employed and that instead of the photoconductive elements 29, 30 and 31, suitable microswitches may be employed. 1

Optical Projections System for Exposure Referring back to FIG. 2, the optical projection system is accommodated within a dust-proof chamber 36 having an upper partition wall 35 which serves to completely separate the optical system from the various devices disposed above, especially from the developing device and the like so that optical elements such as lenses 37 and 38, reflecting mirrors 39, 40 and 41 may be prevented from being contaminated by the toner or the like. In addition, the optical system is arranged to facilitate the assembly, adjustment, inspection and maintenance. In the instant embodiment, two slit exposure devices 42 and 43 are provided so that the original may be exposed or projected twice in one going stroke. That is, the light or radiation image of the original may be projected upon the rotary drum 11 through the first slit exposure device 42, the lens 37 and the reflecting mirrors 39 and 41 along the optical path P1. In the similar manner the light or radiation image of the original may be projected upon the rotary drum through the second slit-exposure device 43, the lens 38, and reflecting mirrors 40-and 41 along the optical path P It is noted that the light or radiation image is projected through the simultaneous exposure-charging device 14. When the light or radiation image from the slit exposure device 42 is projected, the light entering into the lens 38 is interrupted by a shutter 44 whereas the light or radiation image is projected through the exposure device 43, the optical path P, is interrupted by a shutter 44' in front of the lens 37. The actuation of these shutters 44 and 44 is controlled by an electromagnet clutch which is energized in response to the actuation of a microswitch which in turn is actuated by the rotary drum.

The instant embodiment has been described as being applied to carry out the electrophotographic process of the type described, but it is understood that the present invention may be also applied to other electrophotographic processes for example as disclosed in the US. Pat. Nos. 2,221,776, 2,357,809 and 2,297,69l, in which the electrostatic charge is uniformly imparted to an electrophotographically sensitive body consisting of an electrically conducting support and an electrophotographically sensitive layer applied thereon; an electrostatic latent image is formed upon the sensitive body by projection of the light or radiation image of an original to be copied; the latent image is developed by use of the toner or the like; and the developed image is transferred to a copying paper or the like.

From the foregoing description, it is seen that the present invention provides a high-speed photocopying machine since more than two exposures or projections of light or radiation images of the original may be made during one reciprocation cycle of the original holder. Therefore, the electrophotographic copying machine of the present invention is particu larly adapted to make only a few copies from a single original as in the case of copying a bill or the like. In addition, the present invention may eliminate the troublesome operation of placing the original in correct position because the original may be automatically placed in desired position on the original holder.

through said slit the radiation image of the original upon a photosensitive member at a position,

predetermined exposure 2. An electrophoto claim 1, wherein said original illumination means are light sources disposed for each of said plurality of fixed slits.

graphic copying machine according to 3. An electrophoto claim 1, wherein said photosensitive member is in the form of a drum.

graphic copying machine according to 4. An electrophoto claim 2 wherein only one of said original illumination means for the slit through which the radiation image is being projected is turned on. 

1. A slit-exposure type electrophotographic copying machine comprising original holding and transporting means, means for illuminating an original, a plurality of fixed slits spaced apart from each other by a suitable distance along the path of said original holding and transporting means, an optical projection means for each of said plurality of fixed slits including a projection lens for projecting through said slit the radiation image of the original upon a photosensitive member at a predetermined exposure position, said photosensitive member being displaced in synchronism with the transportation of said original holding and transporting means, and drive means for driving both of said original holding and transporting means and said photosensitive member.
 2. An electrophotographic copying machine according to claim 1, wherein said original illumination means are light sources disposed for each of said plurality of fixed slits.
 3. An electrophotographic copying machine according to claim 1, wherein said photosensitive member is in the form of a drum.
 4. An electrophotographic copying machine according to claim 2 wherein only one of said original illumination means for the slit through which the radiation image is being projected is turned on. 